The Brand New Adcom 555SE and 585SE Sound Great

Not yet, as far as I know. Lots of reviews in North America and Europe, but nothing from Stereophile or TAS.

 

You’d think they would, given its place in Amp history. Kind of like how they’re silent on the L100.

 

By "these things" I meant the protection and "true balanced". These are not addressed in the first post you suggest, which I, of course, have read before posting. Also, as mentioned earlier, I've read the manual and I found no clear answer to my questions.

Where can I see the evidence that the protection issue from the past is solved on the SE generation? Every online discussion I checked brings up this past issue sooner or later, but no one knows if that's the same with the new 555SE.

Regarding balanced inputs, in another thread you said: "Some component makers add non-balanced XLR connections merely with the hope that the item will look more technical or more advanced to prospective buyers." Can someone explain what a single-ended XLR connection is?
How do we know it's not the case with this amp, like the amazon review suggests?

 

And in this thread I pointed out that the XLR connections clearly have toggle switchs to make them either balanced or unbalanced

[QUOTE="RPM, post: 21647000, member: 68881"]Can someone explain what a single-ended XLR connection is?[/QUOTE]

In an RCA connection (unbalanced by definition), there is a central conductor. In addition, the second conductor is also the shield/ground.

In a balanced XLR connection, there are two conductor wires and a third wire used as a shield/ground.

In an unbalanced XLR connection on a component, either the positive or negative conductor is joined to the ground/shield, and that makes the XLR connection unbalanced. That’s how some cheap component manufacturers wire their XLR connections in lieu of a real balanced circuit (which is a bit more expensive to design and build). So, the Balanced/Unbalanced toggle switches on the back of the 555SE either keep the positive and shield separate (balanced mode) or connect them (unbalanced mode).

Balanced XLR connections are useful primarily in electrically noisy environments where cables runs are dozens of feet long or more. In typical home audio cable runs, balanced XLR connections can solve some component grounding issues that are causing hum. Aside from that, balanced connections don’t offer intrinsically better sound.

 

The context got me confused:
is the above statement in regards to the XLR only? Like, when in unbalanced position the XLR becomes unbalanced? Because I understand the switch differently: it selects between the two inputs - XLR (balanced) and RCA (unbalanced).

 

And I apologize for any confusion. Page 11 (6) of the PDF manual is clear. The toggles switch between the balanced and unbalanced hardware connections. Adcom marketing, tech support and the Adcom rep I know - Lawrence Mitner - stated (and still state) that the XLR connections are true balanced connections. I have no reason to doubt that. Unfortunately, I do not have a 555SE handy to uncase in order to trace wires to find out if they were all BS’ing me.

 

Having Adcom crank out quality value components again can't be a bad thing. I'm curious if they will put out a higher end pre than the one they currently offer.

 

Oh well, guess we'll have to wait for definite clarification.

 

What’s an L100?

 

L100 Classic | 12” 3-way Bookshelf Loudspeaker

 

Oh, yeah. I thought the idea to resurrect them was interesting, but they are just horrendously overpriced.

 

Found this in the GFA 565 SE manual on the Adcom site (funny, the manual omits the SE, maybe it's an old manual?):
"...In addition, no protection or current-limiting circuitry is used in the GFA-565
which could degrade the Signal."
"...Therefore, only fuses on the DC
rails are used for protection."

What are your thoughts on this? Is it dangerous enough not to take the risk?
Can we assume the same goes for the 555SE, since there's no word on this in its manual?

 

This actually has been Adcom’s long-time philosophy—to eliminate protection circuitry out of the signal path. So, the new 565 isn’t doing anything different than the old 555, 555 II, and 565. It doesn’t make the product dangerous to the end user, but you could potentially fry the amp if you accidentally shorted the speaker terminals, for example.

 

I guess this is also a risk?

 

This is a very slight risk on any SS amp (except for a McIntosh which features Auto-transformers on its output). However on an amp without any circuit protection, yes, frying a speaker with DC when an output transistor shorts has been known to happen at times.

 

Actually I'd like to understand better this protection thing. What types of protection are implemented as standard on the usual amp and in what the Adcoms are different?

 

Most SS amps implement various types of signal protection circuitry which is designed to save the amp and/or your speakers in the event of certain dangerous situations. How far this protection goes, and how well it is implemented differs from amp to amp. In its simplest form protection could just be a fuse. But there are endless other possibilities such as employing a sophisticated circuit which monitors the input for dangerous signals, and mutes the outputs in such cases. So it is impossible to generalize very much here.

However in the case of the Adcoms there is no protection circuitry what-so-ever. So if something fails, there is a chance that it may fail spectacularly. But this was a deliberate design decision in the case of the Adcoms because the designers believe that Signal protection circuitry slightly detracts from the performance of the amp.

 

Truly enjoyed following this thread. I appreciate the knowledge, opinions and civil debate put forth here. In an attempt to keep the discussion alive, I am pleased to report that I located a 9/10 condition GFA-555se slated for delivery tomorrow. Cost was $860 USD. It will be paired with a custom built (not by me) tube preamp that has aready proven its abilities, 4312 studio monitors, and a new Fluance RT-85 turntable via a Musical Fidelity phono stage.
It may take a little time to set up the system, since with all the Covid-19 madness, my job is considered "essential", and work hours have been longer than usual. I will be certain to check back here with my thoughts on the amp and setup in general. I don't consider myself an audiophile, but as long as I can add a new (hopefully better) component to my system - and hear an improvement in sound - I will keep said component. In this case, that hopefully will be the soon to arrive GFA-555se.

 

I’ve had an original GFA 555 II in my system for the last 6 or 7 years. As I upgrade around it - components, cables, room treatments - and GAS takes a hold of me, I’m left questioning why I would replace this amazing beast of an amp? The price point of the new 555 has me intrigued but am I even going to realize difference, and is that difference considered an actual upgrade? I feel like this amp punches so far above its weight (read: price) that justifying an upgrade becomes an errand for a fool.

Convince me otherwise?

 

I've owned my GFA-555 II since purchasing it new in March 1993. Listen to it several times a week. When it breaks or develops issues it will be replaced with a newer, better modern amp. But not until then.

M. M.

 

At this point, if I do anything with the amp, I'm seriously considering sending it to Musical Concepts.

 

Wow, Adcom only has 7 dealers in the US. Of course you can buy directly off their website. The amps look every bit as substantial as the old models. The GFA-6002 is a newly refreshed version of the old one and a nice looking replacement for a GFA 535. Prices have gone up about 30% on these amps since I last checked them out a couple of years ago. I wonder how they are doing as a company now support wise?
https://www.adcom.com/allproduct.php

 

There is a cool Adcom fan page on Facebook with a lot of discussion.
Adcom Audio Enthusiasts Group (AAEG)

 

Was the original Adcom amp design by Nelson Pass before he did the Aleph?

 

Yes. In the ‘80s. Pass took a design contract offered by Alec Chenin at Adcom.